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389 Block
Pontiac V8 389 Block
Watch The Compression — 389 Block for Pontiac V8s
389 Block kits serve the engine that built Pontiac's reputation, and it is the one block family where compression needs watching. The 389 uses small chambers by later standards, so a flat top piston can put a rebuild into high-octane-only territory before you have done anything else.
Butler covers the 389 with re-ring kits, rebuild kits in cast or forged pistons with published compression ratios, and Butler budget short blocks and custom short block kits from 395 cubic inches at stock stroke out to 454 at 4.250".
Browse 389 Block Products
Items 1-14 of 14
Description:
Customized Butler Performance Short Block
3.750"Stroke
Great budget friendly package tailored to you
Rated for up to 500hp only
All short blocks...More Details »
Item #: BP-SB-389-3750
Condition:
New
Please Call for Availability
Contact us for lead time
Description:
Customized Butler Performance Short Block
4.000"Stroke
Great budget friendly package tailored to you
Rated for up to 500hp only
All short blocks...More Details »
Item #: BP-SB-389-4000
Condition:
New
Please Call for Availability
Contact us for lead time
Description:
Customized Butler Performance Short Block
4.250"Stroke
Great budget friendly package tailored to you
Rated for up to 500hp only
All short blocks...More Details »
Item #: BP-SB-389-4250
Condition:
New
Please Call for Availability
Contact us for lead time
Description:
Customized Butler Performance Short Block Kit
3.750" Stroke
Great budget friendly package tailored to you
All short blocks undergo the "Butler Process"
Item #: BP-SB-Kit-389-3750
Condition:
New
Please Call for Availability
15-17 weeks (slightly longer for full custom pistons). Ships to business address. Residential or liftgate are available for additional charges
Description:
Customized Butler Performance Short Block Kit
4.0000" Stroke
Great budget friendly package tailored to you
All short blocks undergo the "Butler Process"
Item #: BP-SB-Kit-389-4000
Condition:
New
Please Call for Availability
15-17 weeks (slightly longer for full custom pistons). Ships to business address. Residential or liftgate are available for additional charges
Description:
Customized Butler Performance Short Block Kit
4.250" Stroke
Great budget friendly package tailored to you
All short blocks undergo the "Butler Process"
Item #: BP-SB-Kit-389-4250
Condition:
New
Please Call for Availability
15-17 weeks (slightly longer for full custom pistons). Ships to business address. Residential or liftgate are available for additional charges
Description: Butler Pontiac 389 Re-Ring Kit includes rings, rod bearings, main bearings, and a complete engine gasket kit
Item #: BPI-REBUILDER-RERING-389
Condition:
New
Price: $469.95
Description: Butler Pontiac 400 Rebuild Kit Standard includes Pistons, Pins,, rings, rod bearings, main bearings, and a complete engine gasket kit
Item #: BPI-REBUILDER-REBUILD-CAST-389
Condition:
New
Price: $1,049.95
Description: Butler Pontiac 389 Rebuild Kit Standard includes Pistons, Pins, rings, rod bearings, main bearings, and a complete engine gasket kit
Item #: BPI-REBUILDER-REBUILD-FORGED-389
Condition:
New
Price: $1,349.95
Description: Sealed Power (Speed-Pro) engine ring set for Pontiac 389 — .030" Over (4.093" bore). Cast moly-faced ring pack: 5/64" top, 5/64" second, 3/16" oil. Complete set for one V8.
Item #: SPR-E253K-030
Condition:
New
Price: $167.98
Description: Sealed Power (Speed-Pro) engine ring set for Pontiac 389 — .060" Over (4.123" bore). Cast moly-faced ring pack: 5/64" top, 5/64" second, 3/16" oil. Complete set for one V8.
Item #: SPR-E253K-060
Condition:
New
Price: $139.95
Description: 4.095 1/16 1/16 3/16 TS Classic Race Rings- File Fit (Set)
Item #: TSR-CR3690-95
Condition:
New
Price: $164.63
Description: 4.105 1/16 1/16 3/16 TS Classic Race Rings- File Fit (Set)
Commonly used in 4.100" bore. Must file to fit
Item #: TSR-CR3690-105
Condition:
New
Price: $164.53
Description: 4.120 +5 1/16 1/16 3/16 TS Classic Race Rings- File Fit (Set)
Item #: TSR-CR1008-5
Condition:
New
Price: $179.96
Items 1-14 of 14
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More About 389 Block
1. Re-ring or full rebuild
| Butler Pontiac 389 Re-Ring Kit | Rings in .030 over, Federal Mogul main bearings in standard, .010" or .020" over, Federal Mogul rod bearings in the same sizes, and a complete gasket kit with rear main seal and oil pan gasket options. |
| 389 Rebuild Kit, cast pistons | Pistons, pins and rings in .030, .040 or .060 over on a 5/64, 5/64, 3/16 pack, plus the same Federal Mogul bearing and gasket content. Flat top at -3.5cc, or a -17cc dish available in .058" over. |
| 389 Rebuild Kit, forged pistons | Flat, dish and dome tops in .030, .040 or .060 over, with the option to add a new cast or forged crank. |
2. The compression numbers Butler publishes
This is the part that makes or breaks a 389 rebuild. Read these before you pick a piston.
| Cast flat top, -3.5cc | Roughly 11.1 to 11.3:1 with a 68cc chamber and 10.7 to 10.9:1 with a 72cc chamber. Butler's listing is blunt about it: that combination must use high octane fuel. |
| Cast dish, -17cc | About 9.7 to 9.9:1 at 68cc and 9.3 to 9.5:1 at 72cc. This is the pump gas answer on a small chamber 389. |
| Forged flat top, -2cc | Around 10.73:1 at 72cc, 10.07:1 at 78cc and 9.41:1 at 85cc. |
| Forged dish, -14cc | Around 9.50:1 at 72cc, 8.99:1 at 78cc and 8.47:1 at 85cc. |
3. Short block kits and what each stroke makes
Butler lists the 389 short blocks by the displacement the stroke produces, assembled or unassembled.
| 3.750" stroke, 395 to 400 ci | The factory stroke, on 6.625" I-beam rods. |
| 4.000" stroke, 421 to 427 ci | Forged crank, with 6.700" H-beam rods in the kit version. |
| 4.250" stroke, 447 to 454 ci | Cast or forged crank on 6.800" H-beam rods. |
| Budget short blocks | Butler's budget 389 packages are rated for up to 500 horsepower. If the plan is more than that, step up to the custom short block. |
| Included either way | Internally balanced rotating assembly, Total Seal file fit rings, performance rod and main bearings, Viton rear main seal and a fully prepped block. |
4. Rings on their own
| Sealed Power | Replacement sets at .030" over, 4.093", and .060" over, 4.123", in a 5/64, 5/64, 3/16 moly-faced pack. |
| Total Seal Classic Race | File fit sets covering 4.090" to 4.093" as a 4.095" ring, 4.100" as a 4.105" ring, and 4.120" to 4.123" as a 4.125" ring. |
| Ring thickness | The 5/64 pack suits a cast replacement piston. The 1/16, 1/16, 3/16 Total Seal pack suits a modern forged piston. The groove in the piston decides it, not the block. |
Tell Butler your chamber volume and your measured bore and the 389 kit choice comes down to one piston and one ring set. Skip that step and the compression ratio will pick you instead, and on a small chamber 389 it will not pick pump gas.
Not sure what your Pontiac needs?
Call our tech team at 866-762-7527. Tell us your engine, heads, car, and power goal, and we will put the parts together as one combination that works.